Mechanism of Benefit of Negative Inotropes in Obstructive Hypertrophic Cardiomyopathy

Abstract

Background-Drugs with negative inotropic effect are widely used to decrease obstruction in hypertrophic cardiomyopathy (HCM). However, the mechanism of therapeutic benefit has not been studied. Methods and Results-We used M-mode, two-dimensional, and pulsed Doppler echocardiography to study 11 patients with obstructive HCM before and after medical elimination of left ventricular outflow tract obstruction. We measured 148 digitized pulsed Doppler tracings recorded in the left ventricular cavity 2.5 cm apical of the mitral valve. Successful treatment slowed average acceleration of left ventricular ejection by 34% (Pϭ.001). Mean time to peak velocity in the left ventricle was prolonged 31% (Pϭ.001). Mean time to an ejection velocity of 60 cm/s was prolonged 91% (Pϭ.001). Before treatment, left ventricular ejection velocity peaked in the first half of systole; after successful treatment, it peaked in the second half (Pϭ.001). In contrast, after treatment, we found no change in peak left ventricular ejection velocity. We also found no change in the distance between the mitral coaptation point and the septum, as measured in two planes, indicating no treatment-induced alteration of this anatomic relationship. Conclusions-Medical

Quantitative left ventricular contractility analysis under stress: a new practical approach in follow-up of hypertensive patients

“…The effects were similar in patients with hypertrophic cardiomyopathy. 36 In addition to LV regional features, hypertensive patients usually develop LV cavity obliteration (Figures 4a and b). Secknus et al 37 have demonstrated that LV cavity obliteration (a consistent finding in LV hypercontractility), frequently respond to dobutamine echocardiography and this may indicate a favourable outcome.…”

Dobutamine Stress Echocardiography Unmasks Acute Worsening of Mitral Regurgitation with Latent Left Ventricular Outflow Tract Obstruction Behind Diastolic Heart Failure in Hypertensive Heart Disease

“…Hi g h e r -p o we r p h o t o mi c r o g r a p h o f a s e r i a l s e c t i o n s h o wn i n P a n e l a ( Ri g h t , Ma s s o n t r ic h r o me s t a i n i n g ) s h o ws t h i c k e n e d s ma l l a r t e r y ( a r r o w) wi t h p e r i v a s c u l a r f i b r o s i s ( a r r o wh e a d s ) . S c a l e b a r s : L e f t , Ri g h t , 5 0 μ (12)(13)(14)(15)(16)(17). The effects have been explained by the negative inotropic action, resulting in ventricular afterload reduction and deceleration of the LV ejection acceleration (13).…”

“…S c a l e b a r s : L e f t , Ri g h t , 5 0 μ (12)(13)(14)(15)(16)(17). The effects have been explained by the negative inotropic action, resulting in ventricular afterload reduction and deceleration of the LV ejection acceleration (13). Hamada et al (16,17) …”

Usefulness of Left Parasternal Approach for the Continuous-Wave Doppler Measurement of Left Ventricular Outflow Tract Pressure Gradient in Patients With Hypertrophic Cardiomyopathy

“…Left ventricular outflow tract (LVOT) obstruction is an important complication of hypertrophic cardiomyopathy, related to symptoms, functional limitations, and prognoses of the patients [1][2][3], and various types of medical and surgical interventions are performed to reduce the pressure gradient in LVOT [4][5][6][7][8][9][10][11][12][13][14][15]. The degree of dynamic obstruction seen in patients with hypertrophic obstructive cardiomyopathy (HOCM) can vary markedly by the physiological changes in preload, contractility, and afterload [16][17][18].…”

“…Transthoracic continuous-wave (CW) Doppler technique has been reported to be feasible to measure the peak velocity in LVOT and to calculate the pressure gradient through the simplified Bernoulli equation [19][20][21]. This method is completely noninvasive and in recent years has become a standard method to quantify the degree of LVOT obstruction and monitor the efficacy of the treatment [8][9][10][11][12][13][14]17].…”